This invention relates to tube bending apparatus, and more particularly relates to a novel and improved method and apparatus for quickly and accurately changing die sets for different-sized tubing to be bent or for different types of tube bending operations.
Tube bending operations require precise alignment between a bend die, pressure die and clamping die for each size of tube to be bent. In many cases, a wiper die is required along with a mandrel which is inserted into the tube portion to be bent. In the standard bending operation, holders are provided on the bend die table which are movable into engagement with the bend and clamping dies, and the pressure die is advanced linearly as the bend die is rotated with the tube to be bent being securely clamped in complementary grooves therebetween to undergo bending and assume the configuration of the grooves as pressure is applied. In many tube bending operations, a mandrel must be inserted into the tube to be bent in order to prevent wrinkling or collapse of the portion of the tube being bent; and in many cases, a wiper die is employed in cooperation with the pressure die to regulate the pressure applied to the tubing during the bending operation.
In changing the various dies for different-sized tubing, the standard practice has been to individually remove the dies and reassemble a new die set onto the table which is time-consuming and results in considerable downtime. In certain tube bending applications, it has been proposed to be able to remove more than one component part of the die set in one step or to provide special devices to facilitate replacement of the die set in an effort to reduce downtime and, for example, reference is made to U.S. Pat. Nos. 4,178,788 to R. T. Zollweg et al, 4,355,525 to J. W. Carson, 4,967,585 to S. Grimaldo, 5,148,695 to H. S. Ellis, 5,339,670 to A. Granelli, 5,426,965 to W. G. Hopf and 5,499,521 to M. E. Luikart et al. Nevertheless, to the best of our knowledge, no one has devised a one-step operation in which component dies of the tube bending apparatus can be removed from the bending table and stored in assembled form so as to retain the same precise alignment and relationship established from the previous bending operation. In this way, the apparatus can be remounted on the table as one unit and remain in the desired relationship so as not to require extensive set-up time in preparing for the next bending operation for that particular sized tubing; and further wherein the die set or kit is so assembled and arranged as to facilitate automated removal and reinstallation with respect to a standard die table as well as the ability to rapidly and accurately locate one or more die sets at one time with respect to the bend die table.